Typically, the heat shield covering a manifold ring in a gas turbine engine is in the form of two complementary portions each surrounding part of a cross-section of the manifold ring, extending around the entire circumference of the manifold ring, and attached thereto through welded or brazed joints. As such, the material of the heat shield must be adapted for welding to the manifold ring, which limits the selection of possible materials that can be used. The welded or brazed joint is also generally highly stressed due to a difference in thermal growth between the heat shield and the manifold ring. The welded or brazed joints further usually act as heat input points transferring heat from the heat shield to the manifold ring, thus causing a temperature increase in the fuel flowing therein. In addition, repairs to the heat shield itself or to other parts of the manifold assembly, for example the fuel spray tip assemblies, is generally impaired by the fact that the heat shield is permanently attached to the manifold ring.
Moreover, a heat shield portion forming a “complete ring”, i.e. extending around the entire circumference of the manifold ring, is generally subjected to high hoop stresses and high vibration stresses, which both limit the life of the heat shield.
In addition, the heat shield portions are usually manufactured through a stamping operation of sheet metal material which, because of the heat shield geometry, generally leads to significant waste of the metal material during the manufacturing process.
Accordingly, improvements are desirable.